Honing mandrels and other tools having a variety of radially or sidewardly extendable or expandable work engaging portions are well known in the art. Known expandable honing mandrel constructions such as shown in Sunnen U.S. Pat. No. 2,376,851, can include one or more work engaging portions such as abrasive stone assemblies or the like which portions are radially expanded or extended by the manipulation or other movement of adjusting or operator means such as an adjusting or wedge member extending through a passageway or slot in the mandrel body. Moving the adjusting or wedge member in a first longitudinal direction in the slot supportively engages and radially extends the stone assembly or other work engaging portion such that the surfaces thereof engage and apply or exert radially directed pressure against an internal surface of a bore or hole or other surface of a workpiece to be honed. When a honing operation is complete or it is otherwise desired to withdraw the honing mandrel from a bore, the wedge member can be moved in a second direction to remove support for the stone assembly and relieve the radially outwardly directed honing pressure enabling the stone assembly to freely move or retract radially inwardly. The stone assembly can then be partially pressed or urged into the mandrel by engagement of the stone with the surface of the bore as the mandrel is withdrawn therefrom. Such known mandrels can also include stone retainer means which bias the stone assembly radially inwardly to some extent.
One shortcoming of such known radially expandable honing mandrel constructions is that the stone assembly may not be fully retracted from contact with the surface of the bore and by the stone retaining means which may further act only to retract one end of the stone assembly such that the opposite end remains extended. This can then require manually or otherwise pinching or pressing the stone assembly more fully into the mandrel to make the mandrel diameter small enough to be inserted into the next part to be honed which will have a smaller bore than the previous honed part. The requirement of pressing the stone assembly into the mandrel takes more time, provides an opportunity for mishandling and makes automatic or robotic parts loading more difficult. Another shortcoming is that the stone assembly can cause scratches or other damage on the honed surface if the extended stone assembly is pressed into the mandrel by contact with the honed surface as the mandrel is withdrawn from the bore.
Another shortcoming of some known constructions is that the stone assemblies are not adequately retained or maintained in the mandrel body enabling the stone assemblies to fly out or become misaligned or mispositioned in the mandrel and damaged or lost due to the centrifugal force created as the mandrel is rotated outside of a part. Still another shortcoming can be mispositioning and lifting or tilting of the wedge member or other operator means as the wedge member is moved for removing support for the work engaging portion.
Other known mandrel constructions such as shown in Sunnen U.S. Pat. Nos. 2,376,850, and 2,421,470, disclose hone sections having angularly extending projections adapted to seat and slide in grooves of an adjusting bar to produce radial movement inwardly and outwardly of the hone sections as the adjusting bar is moved in opposite axial directions. An important limitation of such known constructions, however, is that they are not particularly adaptable for use in mandrels for honing relatively small bores such as below one inch and as small as 0.1 inch in diameter as the angularly extending projections would become too small for supporting the hone sections and the adjusting bar would become too narrow at the grooves to withstand the honing pressures used in many honing operations.
Contrasted to the relatively limited constructions discussed above, the subject invention relates to relatively uncomplicated, reliable and trouble free means for positively retracting and retaining the radially expandable work engaging portions of a honing mandrel for such purposes as facilitating automatic and robotic parts loading, reducing damaging contact between the work engaging portion and the honed surface, preventing the work engaging portion from flying out of the mandrel or becoming mispositioned or lost and preventing tilting of the adjusting or operator means, which retracting and retaining means can be made for use with a wide variety of mandrel constructions including for honing relatively small bores.